Fe16N2 Iron-Nitride Magnet Microstructure for Rare-Earth-Free Energy
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Solution Overview
Problem
Current permanent magnets rely on rare earth elements, which are scarce and costly to produce, leading to environmental concerns due to high manufacturing costs and mining impacts, and existing magnets have lower energy products compared to those with Fe16N2.
Innovation Solution
Development of bulk permanent magnets incorporating the Fe16N2 phase with a polycrystalline microstructure of elongated crystallographic grains, produced through a process involving annealing, nitriding, stress annealing, and magnetic field annealing, which enhances magnetic properties and reduces reliance on rare earth elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth elements (neodymium) are used in permanent magnets, then high energy product is achieved, but manufacturing cost increases and environmental impact worsens
Solution Approach 1:
The patent changes the material composition parameters by replacing rare earth elements with iron-rich compositions containing Fe16N2 phase, achieving high energy product through compositional substitution rather than using expensive rare earth materials
Solution Approach 2:
The patent substitutes expensive rare earth elements with cheaper iron-based materials, using abundant and inexpensive raw materials to achieve comparable or superior magnetic performance without relying on scarce resources
2Reliability
If rare earth elements are used in permanent magnets, then high energy product is achieved, but environmental deterioration increases
Solution Approach 1:
The patent extracts and eliminates rare earth elements from the magnet composition, removing the source of environmental harm associated with their mining and processing while retaining high energy product performance through iron-based alternatives
Solution Approach 2:
By using abundant iron-based materials instead of scarce rare earth elements, the patent reduces environmental impact associated with mining and processing rare earth metals, substituting harmful material extraction with cleaner production processes
3Productivity
If conventional sintering process is used for NdFeB and ferrite magnets, then magnet production is achieved, but manufacturing cost increases due to high temperatures and complex processing
Solution Approach 1:
The patent changes the processing parameters by using lower temperature fabrication methods and simplified processing steps compared to conventional sintering, reducing energy consumption and manufacturing costs while maintaining production capability
Solution Approach 2:
By using iron-based compositions that can be processed more economically than rare earth magnets, the patent reduces manufacturing costs associated with high-temperature sintering and complex fabrication processes
4Reliability
If Fe16N2 phase is used in permanent magnets, then higher energy product is achieved, but material composition complexity increases
Solution Approach 1:
The patent optimizes the compositional parameters of iron-based materials to achieve the Fe16N2 phase, using controlled amounts of alloying elements to facilitate phase formation while maintaining relatively simple overall composition compared to rare earth magnets
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Fe16N2-based magnets offer higher energy products, up to 134 MGOe, and lower environmental impact by eliminating the need for rare earth elements, improving efficiency and reducing production costs.
Implementation Method 1
carrying out a microstructure build-up by annealing the prepared raw material at an elevated temperature
Implementation Method 2
quenching the nitrided material to a martensitic transformation temperature
Implementation Method 3
quenching the nitrided material to a martensitic transformation temperature to produce a martensite structure
Implementation Method 4
stress annealing the nitrided material
Implementation Method 5
magnetic field annealing the nitrided material
Implementation Method 6
Fe16N2 has high saturation magnetization and magnetic anisotropy constant
Data Source
AI summary
The disclosure is directed to an iron-nitride material having a polycrystalline microstructure including a plurality of elongated crystallographic grains with grain boundaries, the iron-nitride material including at least one of an α″-Fe16N2 phase and a body-center-tetragonal (bct) phase comprising Fe and N. The disclosure is also directed a method producing an iron-nitride material. The method includes some combinations of preparing a raw material comprising iron, carrying out a microstructure build-up by annealing the prepared raw material at an elevated temperature and subsequently quenching the prepared raw material to produce a microstructure build-up material, annealing the microstructure build-up material, reducing the microstructure build-up material in a hydrogen environment, nitriding the reduced material to produce a nitrided material and subsequently quenching the nitrided material to a martensitic transformation temperature, stress annealing the nitrided material, and magnetic field annealing the stress-annealed material.